Versatile oxidation byproduct purge process

ABSTRACT

Disclosed is a process and apparatus for treating a purge stream in a carboxylic acid production process. The process employs a purge process that allows for the separation of oxidation byproducts into benzoic acid and non-benzoic acid oxidation byproducts, thus providing flexibility in the treatment and use of such oxidation byproducts.

RELATED APPLICATIONS

This application claims the priority benefit of U.S. Provisional Pat.App. Ser. Nos. 60/777,829; 60/777,903; 60/777,905; 60/777,907;60/777,992; 60/778,117; 60/778,120; 60/778,123; and 60/778,139, allfiled Mar. 1, 2006, the entire disclosures of which are incorporatedherein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to a purge process for use inthe production of a carboxylic acid. More specifically, the presentinvention relates to the use of a purge process for separating androuting various oxidation byproducts formed in a terephthalic acidproduction process.

2. Description of the Prior Art

In conventional terephthalic acid (TPA) production processes,para-xylene undergoes oxidation. In such processes, oxidation byproductsare produced along with the formation of TPA. Typically, such oxidationbyproducts include the oxidation intermediates and side reactionproducts formed in the oxidation of para-xylene, as well as anyimpurities originating from the raw materials. Some of these byproductsare detrimental to the use of TPA in various production processes, suchas for the production of polyethylene terephthalate (PET), dimethylterephthalate (DMT), or cyclohexane dimethanol (CHDM). Accordingly, atleast a portion of these detrimental oxidation byproducts are typicallyremoved from the TPA production process in order to yield a commerciallyusable TPA product. On the other hand, some oxidation byproducts are notdetrimental to these production processes. In fact, some oxidationbyproducts, such as bifunctional compounds, are actually useful in a PETproduction process.

It is known in the art to employ a purge process to remove oxidationbyproducts from TPA production processes, thus rendering the TPA productsuitable for use in the various above-mentioned production processes. Apurge process typically involves separating a portion of a motherliquor, generated from the separation of liquid from the product stream,to form a purge feed stream. The purge feed stream generally constitutesin the range of from 5 to 40 percent of the total mother liquor, but canbe up to 100 percent of the mother liquor. In a typical conventionalpurge process, the purge feed stream contains acetic acid, catalyst,water, oxidation byproducts, and minor amounts of terephthalic acid. Thepurge feed stream in conventional processes is usually resolved into acatalyst rich stream and an oxidation byproduct rich stream. Thecatalyst rich stream is typically recycled to the oxidizer, whereas theoxidation byproduct rich stream is usually routed out of the TPAproduction process for waste treatment or destruction. In such aconventional process, the oxidation byproduct rich stream contains allof the different types of byproducts generated in the oxidation step.Thus, conventional purge processes expel both detrimental andnon-detrimental oxidation byproducts from the TPA production process.

Accordingly, there is a need for a purge process that can differentiatedetrimental oxidation byproducts from non-detrimental and/or beneficialoxidation byproducts. Such differentiation enables the operator to allowsome or all of the non-detrimental and/or beneficial oxidationbyproducts to exit the TPA production process along with the TPA productin order to increase product yield and decrease costs associated withwaste treatment.

SUMMARY OF THE INVENTION

One embodiment of the present invention concerns a process for treatinga purge feed stream comprising oxidation byproducts, wherein theoxidation byproducts include benzoic acid (BA) and non-BA byproducts.The process of this embodiment comprises: separating at least a portionof the purge feed stream into a BA rich stream and a non-BA byproductrich stream.

Another embodiment of the present invention concerns a terephthalic acid(TPA) production process comprising: (a) oxidizing an aromatic compoundto thereby produce a slurry comprising TPA and oxidation byproducts,wherein the oxidation byproducts include benzoic acid (BA) and non-BAbyproducts; and (b) substantially isolating the TPA from the slurry tothereby produce a TPA product, wherein the cumulative rate at which thenon-BA byproducts exit the TPA production process with the TPA productand/or are combined with the TPA product downstream of the TPAproduction process is at least about 5 percent of the make-rate of thenon-BA byproducts in the TPA production process.

Still another embodiment of the present invention concerns a process fortreating a purge feed stream comprising impurities and one or morecatalyst components. The process of this embodiment comprises:separating the purge feed stream into a mono-functional impurity richstream, a mono-functional impurity depleted stream, and a catalyst richstream.

BRIEF DESCRIPTION OF THE DRAWING FIGURES

A preferred embodiment of the present invention is described in detailbelow with reference to the attached drawing figures, wherein:

FIG. 1 is a process flow diagram illustrating a system for theproduction and purification of carboxylic acid constructed in accordancewith the present invention, particularly illustrating a configurationwhere the crude slurry from the oxidation reactor is subjected topurification, the resulting purified slurry is subjected to productisolation, and a portion of the mother liquor from the product isolationzone is employed as a feed to a purge treatment system;

FIG. 2 is a process flow diagram illustrating an overview of a purgetreatment system constructed in accordance with a first embodiment ofthe present invention, particularly illustrating a configuration wherethe purge feed stream is subjected to non-benzoic acid (non-BA)byproduct removal and the resulting catalyst and benzoic acid (BA) richmother liquor is subjected to BA removal;

FIG. 3 is a process flow diagram illustrating in detail a purgetreatment system constructed in accordance with a first configuration ofthe first embodiment of the present invention, particularly illustratinga configuration where the purge feed stream is subjected toconcentration, the resulting concentrated purge stream is subjected tosolid/liquid separation, the resulting catalyst and BA rich motherliquor is subjected to concentration, and the resulting concentratedcatalyst and BA rich mother liquor is subjected to BA/catalystseparation;

FIG. 4 is a process flow diagram illustrating in detail a purgetreatment system constructed in accordance with a second configurationof the first embodiment of the present invention, particularlyillustrating a configuration where the purge feed stream is subjected toconcentration, the resulting concentrated purge stream is subjected tosolid/liquid separation, the resulting catalyst and BA rich motherliquor is subjected to catalyst removal, and the resulting BA andsolvent rich stream is subjected to BA/solvent separation;

FIG. 5 is a process flow diagram illustrating an overview of a purgetreatment system constructed in accordance with a second embodiment ofthe present invention, particularly illustrating a configuration wherethe purge feed stream is subjected to BA removal and the resultingcatalyst and non-BA byproduct rich stream is subjected to non-BAbyproduct removal; and

FIG. 6 is a process flow diagram illustrating in detail a purgetreatment system constructed in accordance with the second embodiment ofthe present invention, particularly illustrating a configuration wherethe purge feed stream is subjected to concentration, the resultingconcentrated purge stream is subjected to BA separation, the resultingcatalyst and non-BA byproduct rich stream is reslurried, and thereslurried catalyst and non-BA byproduct rich stream is subjected tosolid/liquid separation.

DETAILED DESCRIPTION

FIG. 1 illustrates an embodiment of the present invention wherecarboxylic acid produced in an oxidation reactor and purified in apurification reactor is subjected to product isolation/catalyst removal.A portion of the resulting mother liquor from the productisolation/catalyst removal zone is treated in a purge treatment zone andresolved into a catalyst rich stream, a benzoic acid (BA) rich stream,and a non-BA byproduct rich stream. Various embodiments of the purgezone are described in detail below with reference to FIGS. 2-6.

In the embodiment illustrated in FIG. 1, a predominately fluid-phasefeed stream containing an oxidizable compound (e.g., para-xylene), asolvent (e.g., acetic acid and/or water), and a catalyst system (e.g.,cobalt, manganese, and/or bromine) can be introduced into oxidation zone10. A predominately gas-phase oxidant stream containing molecular oxygencan also be introduced into oxidation zone 10. The fluid- and gas-phasefeed streams form a multi-phase reaction medium in oxidation zone 10.The oxidizable compound can undergo partial oxidation in a liquid phaseof the reaction medium contained in oxidation zone 10.

In one embodiment of the present invention, oxidation zone 10 cancomprise an agitated reactor. Agitation of the reaction medium inoxidation zone 10 can be provided by any means known in the art. As usedherein, the term “agitation” shall denote work dissipated into thereaction medium causing fluid flow and/or mixing. In one embodiment,oxidation zone 10 can be a mechanically-agitated reactor equipped withmeans for mechanically agitating the reaction medium. As used herein,the term “mechanical agitation” shall denote agitation of the reactionmedium caused by physical movement of a rigid or flexible element(s)against or within the reaction medium. For example, mechanical agitationcan be provided by rotation, oscillation, and/or vibration of internalstirrers, paddles, vibrators, or acoustical diaphragms located in thereaction medium. In another embodiment of the present invention,oxidation zone 10 can comprise a bubble column reactor. As used herein,the term “bubble column reactor” shall denote a reactor for facilitatingchemical reactions in a multi-phase reaction medium, wherein agitationof the reaction medium is provided primarily by the upward movement ofgas bubbles through the reaction medium. As used herein, the terms“majority,” “primarily,” and “predominately” shall mean more than 50percent.

The oxidizable compound present in the fluid-phase feed streamintroduced into oxidation zone 10 can comprise at least one hydrocarbylgroup. Also, the oxidizable compound can comprise an aromatic compound.In one embodiment, the oxidizable compound can comprise an aromaticcompound with at least one attached hydrocarbyl group or at least oneattached substituted hydrocarbyl group or at least one attachedheteroatom or at least one attached carboxylic acid function (—COOH). Inanother embodiment, the oxidizable compound can comprise an aromaticcompound with at least one attached hydrocarbyl group or at least oneattached substituted hydrocarbyl group with each attached groupcomprising from 1 to 5 carbon atoms. In yet another embodiment, theoxidizable compound can be an aromatic compound having exactly twoattached groups with each attached group comprising exactly one carbonatom and consisting of methyl groups and/or substituted methyl groupsand/or at most one carboxylic acid group. Suitable examples of theoxidizable compound include, but are not limited to, para-xylene,meta-xylene, para-tolualdehyde, meta-tolualdehyde, para-toluic acid,meta-toluic acid, and/or acetaldehyde. In one embodiment of the presentinvention, the oxidizable compound comprises para-xylene.

A “hydrocarbyl group,” as defined herein, is at least one carbon atomthat is bonded only to hydrogen atoms and/or to other carbon atoms. A“substituted hydrocarbyl group,” as defined herein, is at least onecarbon atom bonded to at least one heteroatom and to at least onehydrogen atom. “Heteroatoms,” as defined herein, are all atoms otherthan carbon and hydrogen atoms. “Aromatic compounds,” as defined herein,comprise an aromatic ring and can comprise at least 6 carbon atoms andcan also comprise only carbon atoms as part of the ring. Suitableexamples of such aromatic rings include, but are not limited to,benzene, biphenyl, terphenyl, naphthalene, and other carbon-based fusedaromatic rings.

The amount of oxidizable compound present in the fluid-phase feed streamintroduced into oxidation zone 10 can be in the range of from about 4 toabout 20 weight percent, or in the range of from 6 to 15 weight percent.

The solvent present in the fluid-phase feed stream introduced intoprimary oxidation reactor 10 can comprise an acid component and a watercomponent. The solvent can be present in the fluid-phase feed stream ata concentration in the range of from about 60 to about 98 weightpercent, in the range of from about 80 to about 96 weight percent, or inthe range of from 85 to 94 weight percent. The acid component of thesolvent can be an organic low molecular weight monocarboxylic acidhaving from 1 to 6 carbon atoms, or 2 carbon atoms. In one embodiment,the acid component of the solvent can comprise acetic acid. The acidcomponent can make up at least about 75 weight percent of the solvent,at least about 80 weight percent of the solvent, or in the range of from85 to 98 weight percent of the solvent, with the balance being water.

As mentioned above, the fluid-phase feed stream introduced intooxidation zone 10 can also include a catalyst system. The catalystsystem can be a homogeneous, liquid-phase catalyst system capable ofpromoting at least partial oxidation of the oxidizable compound. Also,the catalyst system can comprise at least one multivalent transitionmetal. In one embodiment, the catalyst system can comprise cobalt,bromine, and/or manganese.

When cobalt is present in the catalyst system, the fluid-phase feedstream can comprise cobalt in an amount such that the concentration ofcobalt in the liquid phase of the reaction medium is maintained in therange of from about 300 to about 6,000 parts per million by weight(ppmw), in the range of from about 700 to about 4,200 ppmw, or in therange of from 1,200 to 3,000 ppmw. When bromine is present in thecatalyst system, the fluid-phase feed stream can comprise bromine in anamount such that the concentration of bromine in the liquid phase of thereaction medium is maintained in the range of from about 300 to about5,000 ppmw, in the range of from about 600 to about 4,000 ppmw, or inthe range of from 900 to 3,000 ppmw. When manganese is present in thecatalyst system, the liquid-phase feed stream can comprise manganese inan amount such that the concentration of manganese in the liquid phaseof the reaction medium is maintained in the range of from about 20 toabout 1,000 ppmw, in the range of from about 40 to about 500 ppmw, or inthe range of from 50 to 200 ppmw.

In one embodiment of the present invention, cobalt and bromine can bothbe present in the catalyst system. The weight ratio of cobalt to bromine(Co:Br) in the catalyst system can be in the range of from about 0.25:1to about 4:1, in the range of from about 0.5:1 to about 3:1, or in therange of from 0.75:1 to 2:1. In another embodiment, cobalt and manganesecan both be present in the catalyst system. The weight ratio of cobaltto manganese (Co:Mn) in the catalyst system can be in the range of fromabout 0.3:1 to about 40:1, in the range of from about 5:1 to about 30:1,or in the range of from 10:1 to 25:1.

During oxidation, the oxidizable compound (e.g., para-xylene) can becontinuously introduced into oxidation zone 10 at a rate of at leastabout 5,000 kilograms per hour, at a rate in the range of from about10,000 to about 80,000 kilograms per hour, or in the range of from20,000 to 50,000 kilograms per hour. During oxidation, the ratio of themass flow rate of the solvent to the mass flow rate of the oxidizablecompound entering oxidation zone 10 can be maintained in the range offrom about 2:1 to about 50:1, in the range of from about 5:1 to about40:1, or in the range of from 7.5:1 to 25:1.

The predominately gas-phase oxidant stream introduced into oxidationzone 10 can comprise in the range of from about 5 to about 40 molepercent molecular oxygen, in the range of from about 15 to about 30 molepercent molecular oxygen, or in the range of from 18 to 24 mole percentmolecular oxygen. The balance of the oxidant stream can be comprisedprimarily of a gas or gases, such as nitrogen, that are inert tooxidation. In one embodiment, the oxidant stream consists essentially ofmolecular oxygen and nitrogen. In another embodiment, the oxidant streamcan be dry air that comprises about 21 mole percent molecular oxygen andabout 78 to about 81 mole percent nitrogen. In an alternative embodimentof the present invention, the oxidant stream can comprise substantiallypure oxygen.

During liquid-phase oxidation in oxidation zone 10, the oxidant streamcan be introduced into oxidation zone 10 in an amount that providesmolecular oxygen somewhat exceeding the stoichiometric oxygen demand.Thus, the ratio of the mass flow rate of the oxidant stream (e.g., air)to the mass flow rate of the oxidizable compound (e.g., para-xylene)entering oxidation zone 10 can be maintained in the range of from about0.5:1 to about 20:1, in the range of from about 1:1 to about 10:1, or inthe range of from 2:1 to 6:1.

The liquid-phase oxidation reaction carried out in oxidation zone 10 canbe a precipitating reaction that generates solids. In one embodiment,the liquid-phase oxidation carried out in oxidation zone 10 can cause atleast about 10 weight percent of the oxidizable compound (e.g.,para-xylene) introduced into oxidation zone 10 to form solids (e.g.,crude terephthalic acid (CTA) particles) in the reaction medium. Inanother embodiment, the liquid-phase oxidation carried out in oxidationzone 10 can cause at least about 50 weight percent of the oxidizablecompound (e.g., para-xylene) introduced into oxidation zone 10 to formsolids (e.g., CTA particles) in the reaction medium. In yet anotherembodiment, the liquid-phase oxidation carried out in oxidation zone 10can cause at least about 90 weight percent of the oxidizable compound(e.g., para-xylene) introduced into oxidation zone 10 to form solids(e.g., CTA particles) in the reaction medium. In one embodiment, thesolids content of the reaction medium can be maintained in the range offrom about 5 to about 40 weight percent, in the range of from about 10to about 35 weight percent, or in the range of from 15 to 30 weightpercent. As used herein, the term “solids content” shall denote theweight percent solids in a multi-phase mixture.

During oxidation in oxidation zone 10, the multi-phase reaction mediumcan be maintained at an elevated temperature in the range of from about125 to about 200° C., in the range of from about 150 to about 180° C.,or in the range of from 155 to 165° C. The overhead pressure inoxidation zone 10 can be maintained in the range of from about 1 toabout 20 bar gauge (barg), in the range of from about 2 to about 12barg, or in the range of from 4 to 8 barg.

In the embodiment of FIG. 1, a crude slurry can be withdrawn from anoutlet of oxidation zone 10 via line 12. The solid phase of the crudeslurry in line 12 can be formed primarily of solid particles of CTA. Theliquid phase of the crude slurry in line 12 can be a liquid motherliquor comprising at least a portion of the solvent, one or morecatalyst components, and minor amounts of dissolved terephthalic acid(TPA). The solids content of the crude slurry in line 12 can be the sameas the solids content of the reaction medium in oxidation zone 10,discussed above.

In one embodiment of the present invention, the crude slurry in line 12can comprise impurities. As used herein, the term “impurities” isdefined as any substance other than TPA, solvent, catalyst, and water.Such impurities can include oxidation byproducts formed during the atleast partial oxidation of the above-mentioned oxidizable compound(e.g., para-xylene) including, but not limited to, benzoic acid (BA),bromo-benzoic acid, bromo-acetic acid, isophthalic acid, trimelliticacid, 2,5,4′-tricarboxybiphenyl, 2,5,4′-tricarboxybenzophenone,para-toluic acid (p-TAc), 4-carboxybenzaldehyde (4-CBA),monocarboxyfluorenones, monocarboxyfluorenes, and/ordicarboxyfluorenones.

In one embodiment of the present invention, the impurities in the crudeslurry in line 12 can be classified according to their functionality ina polyester polymerization process, such as, for example, in theproduction of polyethylene terephthalate (PET). Some impurities can bemono-functional while others can be non-mono-functional in a process forproducing a polyester (e.g., PET). As used herein, an impurity that is“mono-functional” is defined as having only one reactive moiety in aprocess for producing a polyester (e.g., PET). Typically, such reactivemoieties can include carboxyl and/or hydroxyl groups. Mono-functionalimpurities include, but are not limited to, BA, bromo-benzoic acid,bromo-acetic acid, 4-CBA, p-TAc, monocarboxyfluorenones, and/ormonocarboxyfluorenes. Non-mono-functional impurities can comprise anyimpurity having less than or greater than one reactive moiety in aprocess for producing a polyester (e.g., PET). Non-mono-functionalimpurities include, but are not limited to, isophthalic acid,trimellitic acid, 2,5,4′-tricarboxybiphenyl,2,5,4′-tricarboxybenzophenone, and dicarboxyfluorenones.

Subsequent to removal from oxidation zone 10, the crude slurry canoptionally be introduced into purification zone 14 via line 12. In oneembodiment, the crude slurry can be treated in purification zone 14 suchthat the concentration of at least one of the above-mentioned impuritiesin the crude slurry is reduced, thereby producing a purified slurry.Such reduction in the concentration of impurities in the TPA can beaccomplished by oxidative digestion, hydrogenation, and/ordissolution/recrystallization.

In one embodiment of the present invention, the crude slurry fed topurification zone 14 can have a 4-CBA content of at least about 100parts per million based on the weight of the solids in the crude slurry(ppmw_(cs)), in the range of from about 200 to about 10,000 ppmw_(cs),or in the range of from 800 to 5,000 ppmw_(cs). The crude slurry fed topurification zone 14 can have a p-TAc content of at least about 250ppmw_(cs), in the range of from about 300 to about 5,000 ppmw_(cs), orin the range of from 400 to 1,500 ppmw_(cs). The purified slurry exitingpurification zone 14 can have a 4-CBA content of less than about 150parts per million based on the weight of the solids in the purifiedslurry (ppmw_(ps)), less than about 100 ppmw_(ps), or less than 50ppmw_(ps). The purified slurry exiting purification zone 14 can have ap-TAc content of less than about 300 ppmw_(ps), less than about 200ppmw_(ps), or less than 150 ppmw_(ps). In one embodiment, treatment ofthe crude slurry in purification zone 14 can cause the purified slurryexiting purification zone 14 to have a 4-CBA and/or p-TAc content thatis at least about 50 percent less than the 4-CBA and/or p-TAc content ofthe crude slurry fed to purification zone 14, at least about 85 percentless, or at least 95 percent less. By way of illustration, if the 4-CBAcontent of the crude slurry fed to purification zone 14 is 200 ppmw_(cs)and the 4-CBA content of the purified slurry exiting purification zone14 is 100 ppmw_(ps), then the 4-CBA content of the purified slurry is 50percent less than the 4-CBA content of the crude slurry.

In one embodiment of the present invention, the crude slurry can besubjected to purification by oxidative digestion in purification zone14. As used herein, the term “oxidative digestion” denotes a processstep or steps where a feed comprising solid particles is subjected tooxidation under conditions sufficient to permit oxidation of at least aportion of the impurities originally trapped in the solid particles.Purification zone 14 can comprise one or more reactors or zones. In oneembodiment, purification zone 14 can comprise one or moremechanically-agitated reactors. A secondary oxidant stream, which canhave the same composition as the gas-phase oxidant stream fed tooxidation zone 10, can be introduced into purification zone 14 toprovide the molecular oxygen required for oxidative digestion.Additional oxidation catalyst can be added if necessary. In analternative embodiment of the present invention, a stream comprisinghydrogen can be introduced into purification zone 14 for at leastpartial hydrogenation of the crude slurry.

When oxidative digestion is employed in purification zone 14, thetemperature at which oxidative digestion is carried out can be at leastabout 10° C. greater than the temperature of oxidation in oxidation zone10, in the range of from about 20 to about 80° C. greater, or in therange of from 30 to 50° C. greater. The additional heat required for theoperation of purification zone 14 can be provided by supplying avaporized solvent to purification zone 14 and allowing the vaporizedsolvent to condense therein. The oxidative digestion temperature inpurification zone 14 can be maintained in the range of from about 180 toabout 240° C., in the range of from about 190 to about 220° C., or inthe range of from 200 to 210° C. The oxidative digestion pressure inpurification zone 14 can be maintained in the range of from about 100 toabout 350 pounds per square inch gauge (psig), in the range of fromabout 175 to about 275 psig, or in the range of from 185 to 225 psig.

In one embodiment of the present invention, purification zone 14 caninclude two digestion reactors/zones—an initial digester and a finaldigester. When purification zone 14 includes an initial digester and afinal digester, the final digester can be operated at a lowertemperature and pressure than the initial digester. In one embodiment,the operating temperature of the final digester can be at least about 2°C. lower than the operating temperature of the initial digester, or inthe range of from about 5 to about 15° C. lower than the operatingtemperature of the initial digester. In one embodiment, the operatingpressure of the final digester can be at least about 5 psig lower thanthe operating pressure of the initial digester, or in the range of fromabout 10 to about 50 psig lower than the operating pressure of theinitial digester. The operating temperature of the initial digester canbe in the range of from about 195 to about 225° C., in the range of from205 to 215° C., or about 210° C. The operating pressure of the initialdigester can be in the range of from about 215 to about 235 psig, orabout 225 psig. The operating temperature of the final digester can bein the range of from about 190 to about 220° C., in the range of from200 to 210° C., or about 205° C. The operating pressure of the finaldigester can be in the range of from about 190 to 210 psig, or about 200psig.

In one embodiment of the present invention, purification zone 14 cancomprise optional first and second solvent swap zones. Optional firstand second solvent swap zones can operate to replace at least a portionof the existing solvent in a slurry with a replacement solvent.Equipment suitable for such replacement includes, but is not limited to,a decanter centrifuge followed by a reslurry with replacement solvent, adisc stack centrifuge, an advancing front crystallizer, or multipledecanter centrifuges with optional counter current washing. Thereplacement oxidation solvent can have substantially the samecomposition as the solvent introduced into oxidation zone 10, asdescribed above.

In one embodiment, the crude slurry fed to purification zone 14 can betreated in the optional first solvent swap zone prior to purification ofthe crude slurry by the above-mentioned oxidative digestion. In anotherembodiment, a purified slurry resulting from oxidative digestion of thecrude slurry can be treated in the optional second solvent swap zone.

Optionally, at least a portion of the displaced oxidation solvent fromthe optional first and/or second solvent swap zones can be dischargedfrom purification zone 14 via line 38. At least a portion of thedisplaced oxidation solvent in line 38 can be routed to solids removalzone 32 via line 40, purge treatment zone 100 via line 38 a, and/oroxidation zone 10 via line 38 b.

In another embodiment of the present invention, purification zone 14 cancomprise an optional crystallization zone and/or an optional coolingzone. A purified slurry resulting from the above-mentioned oxidativedigestion of the crude slurry can be treated in the optionalcrystallization zone to at least partially increase the particle sizedistribution of the purified slurry. Optional crystallization zone cancomprise any equipment known in the art that can operate to increase theparticle size distribution of the purified slurry. When an optionalcooling zone is employed, the purified slurry can be cooled therein to atemperature in the range of from about 20 to about 195° C. When both acrystallization zone and a cooling zone are employed, the purifiedslurry can be treated first in the crystallization zone and subsequentlyin the cooling zone.

Referring again to FIG. 1, a purified slurry can be withdrawn from anoutlet of purification zone 14 via line 16. The solid phase of thepurified slurry can be formed primarily of purified terephthalic acid(PTA) particles, while the liquid phase can be formed of a motherliquor. The solids content of the purified slurry in line 16 can be inthe range of from about 1 to about 50 percent by weight, in the range offrom about 5 to about 40 weight percent, or in the range of from 20 to35 weight percent. The purified slurry in line 16 can be introduced intoproduct isolation/catalyst removal zone 18 for at least partial recoveryof the solid PTA particles.

Optionally, at least a portion of the crude slurry in line 12 can beintroduced into product isolation/catalyst removal zone 18 via line 12a. As mentioned above, the solid phase of the crude slurry can be formedprimarily of CTA particles, while the liquid phase can be formed of amother liquor. The solids content of the crude slurry in line 12 a canbe in the range of from about 1 to about 50 percent by weight, in therange of from about 5 to about 40 weight percent by weight, or in therange of from 20 to 35 percent by weight. The crude slurry in line 12 acan be introduced into product isolation/catalyst removal zone 18 forrecovery of the solid CTA particles.

Product isolation/catalyst removal zone 18 can separate the crude slurryand/or the purified slurry into a predominately fluid phase motherliquor and a wet cake. Product isolation/catalyst removal zone 18 cancomprise any method of solid/liquid separation known in the art that iscapable of generating a wet cake and a mother liquor stream. Inaddition, it may be desirable for product isolation/catalyst removalzone 18 to have the capability of washing the wet cake. Suitableequipment for use in product isolation/catalyst removal zone 18includes, but is not limited to, a pressure drum filter, a vacuum drumfilter, a vacuum belt filter, multiple solid bowl centrifuges withoptional counter current wash, or a perforated centrifuge.

In one embodiment of the present invention, a wash stream can beintroduced into product isolation/catalyst removal zone 18 to wash atleast a portion of the wet cake generated in product isolation/catalystremoval zone 18, thereby producing a washed wet cake. In one embodiment,the wash stream can comprise acetic acid and/or water. Optionally, afterwashing the wet cake, the used wash liquor can be withdrawn from productisolation/catalyst removal zone 18, and at least a portion of the washliquor can be routed, either directly or indirectly, to oxidation zone10.

The above-mentioned wet cake generated in product isolation/catalystremoval zone 18 can be discharged via line 20. In one embodiment of thepresent invention, the wet cake generated in product isolation/catalystremoval zone 18 can primarily comprise solid particles of TPA. The solidTPA particles can comprise CTA and/or PTA particles. The wet cake cancomprise in the range of from about 5 to about 30 weight percent liquid,in the range of from about 10 to about 25 weight percent liquid, or inthe range of from 12 to 23 weight percent liquid. Additionally, the TPAproduct wet cake in line 20 can comprise oxidation byproducts, asdiscussed above. In one embodiment, the TPA product in line 20 cancomprise a cumulative concentration of mono-functional oxidationbyproducts of less than about 1,000 ppmw, less than about 750 ppmw, orless than 500 ppmw.

In one embodiment of the present invention, the wet cake in line 20 canbe introduced into drying zone 22 via line 20 to thereby produce a dryTPA particulate product comprising solid TPA particles. Drying zone 22can comprise any drying device known in the art that can produce a driedTPA particulate product comprising less than about 5 weight percentliquid, less than about 3 weight percent liquid, or less than 1 weightpercent liquid. Dried TPA particulate product can be discharged fromdrying zone 22 via line 24.

In another embodiment, the wet cake in line 20 can be introduced intosolvent swap zone 26 to produce a wet TPA particulate product comprisingsolid TPA particles. Solvent swap zone 26 can operate to replace atleast a portion of the liquid in the wet cake with a replacementsolvent. Equipment suitable for such replacement includes, but is notlimited to, a decanter centrifuge followed by a reslurry withreplacement solvent, a disc stack centrifuge, an advancing frontcrystallizer, or multiple decanter centrifuges with counter currentwashing. Wet TPA particulate product can be discharged from solvent swapzone 26 via line 28. The wet TPA particulate product can comprise in therange of from about 5 to about 30 weight percent liquid, in the range offrom about 10 to about 25 weight percent liquid, or in the range of from12 to 23 weight percent liquid.

Referring still to FIG. 1, the above-mentioned mother liquor can bedischarged from product isolation/catalyst removal zone 18 via line 30.In one embodiment of the present invention, at least a portion of themother liquor can optionally be introduced into solids removal zone 32.Solids removal zone 32 can comprise any equipment known in the art thatis operable to remove a sufficient amount of solids from the motherliquor to produce a solids-depleted mother liquor comprising less thanabout 5 weight percent solids, less than about 2 weight percent solids,or less than 1 weight percent solids. Suitable equipment that may beemployed in solids removal zone 32 includes a pressure filter, such as,for example, a filter press, a candle filter, a pressure leaf filter,and/or a cartridge filter. In one embodiment, solids removal zone 32 canbe operated at a temperature in the range of from about 20 to about 195°C. and a pressure in the range of from about 750 to about 3750 torrduring solids removal. The solids-depleted mother liquor can bedischarged from solids removal zone 32 via line 34. In one embodiment ofthe present invention, at least a portion of the solids removed from themother liquor in solids removal zone 32 can be discharged via line 36and can be routed to product isolation/catalyst removal zone 18 via line36 a and/or to line 20 via line 36 b.

As mentioned above, at least a portion of the displaced oxidationsolvent from purification zone 14 can also optionally be treated insolids removal zone 32. Such displaced oxidation solvent can bewithdrawn from purification zone 14 via line 38 and introduced intosolids removal zone 32 via line 40. When displaced oxidation solventfrom oxidation zone 14 is treated in solids removal zone 32, theresulting solids-depleted displaced oxidation solvent can be combinedwith the solids-depleted mother liquor and can be discharged via line34.

In one embodiment of the present invention, at least a portion of theoptionally solids-depleted mother liquor in line 34 can be withdrawnfrom line 34 via line 42 to form a purge feed stream. The amount ofmother liquor withdrawn by line 42 to form the purge feed stream can bein the range of from about 1 to about 55 percent of the total weight ofthe mother liquor, in the range of from about 5 to about 45 percent byweight, or in the range of from 10 to 35 percent by weight. Optionally,at least a portion of the displaced oxidation solvent discharged frompurification zone 14 in line 38 can be combined with the purge feedstream via line 38 a. In another embodiment, at least a portion of theremaining mother liquor in line 34 can be routed, either directly orindirectly, to oxidation zone 10 via line 44. Optionally, at least aportion of the wash liquor discharged from product isolation/catalystremoval zone 18 can be combined with at least a portion of the motherliquor in line 44 prior to introduction into oxidation zone 10.

In one embodiment of the present invention, the mother liquor in line34, and consequently the purge feed stream in line 42, can comprisesolvent, one or more catalyst components, oxidation byproducts, and TPA.The solvent in the mother liquor in line 34 and the purge feed stream inline 42 can comprise a monocarboxylic acid. In one embodiment, thesolvent can comprise water and/or acetic acid. The mother liquor in line34 and the purge feed stream in line 42 can comprise solvent in anamount of at least about 85 weight percent, at least about 95 weightpercent, or at least 99 weight percent.

The catalyst components in the mother liquor in line 34 and the purgefeed stream in line 42 can comprise the catalyst components as describedabove with reference to the catalyst system introduced into oxidationzone 10. In one embodiment, the catalyst components can comprise cobalt,manganese, and/or bromine. The mother liquor in line 34 and the purgefeed stream in line 42 can have a cumulative concentration of all of thecatalyst components in the range of from about 500 to about 20,000 ppmw,in the range of from about 1,000 to about 15,000 ppmw, or in the rangeof from 1,500 to 10,000 ppmw.

The oxidation byproducts in the mother liquor in line 34 and the purgefeed stream in line 42 can comprise one or more of the oxidationbyproducts discussed above. In one embodiment, the oxidation byproductsin the mother liquor in line 34 and the purge feed stream in line 42 cancomprise both BA and non-BA byproducts. As used herein, the term “non-BAbyproducts” is defined as any oxidation byproduct that is not benzoicacid. Non-BA byproducts include, but are not limited to, isophthalicacid (IPA), phthalic acid (PA), trimellitic acid,2,5,4′-tricarboxybiphenyl, 2,5,4′-tricarboxybenzophenone, p-TAc, 4-CBA,naphthalene dicarboxylic acid, monocarboxyfluorenones,monocarboxyfluorenes, and/or dicarboxyfluorenones. In one embodiment,the mother liquor in line 34 and the purge feed stream in line 42 cancomprise BA in an amount in the range of from about 500 to about 150,000ppmw based on the weight of the purge feed stream, in the range of fromabout 1,000 to about 100,000 ppmw, or in the range of from 2,000 to50,000 ppmw. Additionally, the mother liquor in line 34 and the purgefeed stream in line 42 can have a cumulative concentration of non-BAbyproducts in the range of from about 500 to about 50,000 ppmw, in therange of from about 1,000 to about 20,000 ppmw, or in the range of from2,000 to 10,000 ppmw.

In one embodiment of the present invention, the mother liquor in line 34and the purge feed stream in line 42 can comprise solids in an amount ofless than about 5 weight percent, less than about 2 weight percent, orless than 1 weight percent. Additionally, the purge feed stream can havea temperature of less than about 240° C., in the range of from about 20to about 200° C., or in the range of from 50 to 100° C.

Referring still to FIG. 1, the purge feed stream can be introduced intoa purge treatment zone 100 via line 42. As will be discussed in greaterdetail below, the purge treatment zone 100 can separate the purge feedstream into a catalyst rich stream, a BA rich stream (i.e., amono-functional impurity rich stream), and a non-BA byproduct richstream (i.e., a mono-functional impurity depleted stream). The BA richstream can be discharged from purge treatment zone 100 via line 48, thecatalyst rich stream can be discharged from purge treatment zone 100 vialine 50, and the non-BA byproduct rich stream can be discharged frompurge treatment zone 100 via line 52.

The BA rich stream in line 48 can have a relatively higher concentrationof BA on a weight basis compared to the BA concentration of the purgefeed stream in line 42. In one embodiment of the present invention, theBA rich stream in line 48 can have a concentration of BA that is atleast about 1.5 times the concentration of BA in the purge feed streamon a weight basis, at least about 5 times the concentration of BA in thepurge feed stream on a weight basis, or at least 10 times theconcentration of BA in the purge feed stream on a weight basis. In oneembodiment, BA can be the primary oxidation byproduct in the BA richstream. Depending of the temperature and pressure of the BA rich streamupon exiting purge treatment zone 100, the BA rich stream in line 48 canpredominately comprise solids or fluid. Thus, in one embodiment, the BArich stream in line 48 can comprise at least about 50 weight percentfluid, at least about 70 weight percent fluid, or at least 90 weightpercent fluid. In an alternate embodiment, the BA rich stream in line 48can comprise at least about 50 weight percent solids, at least about 70weight percent solids, or at least 90 weight percent solids.

The catalyst rich stream in line 50 can have a relatively highercumulative concentration of all of the catalyst components on a weightbasis compared to the cumulative concentration of all of the catalystcomponents in the purge feed stream in line 42. In one embodiment of thepresent invention, the catalyst rich stream in line 50 can have acumulative concentration of all of the catalyst components that is atleast about 1.5 times the cumulative concentration of all of thecatalyst components in the purge feed stream on a weight basis, at leastabout 5 times the cumulative concentration of all of the catalystcomponents in the purge feed stream on a weight basis, or at least 10times the cumulative concentration of all of the catalyst components inthe purge feed stream on a weight basis. Depending of the temperatureand pressure of the catalyst rich stream upon exiting purge treatmentzone 100, the catalyst rich stream in line 50 can predominately comprisesolids or fluid. Thus, in one embodiment, the catalyst rich stream inline 50 can comprise at least about 50 weight percent fluid, at leastabout 70 weight percent fluid, or at least 90 weight percent fluid. Inan alternate embodiment, the catalyst rich stream in line 50 cancomprise at least about 50 weight percent solids, at least about 70weight percent solids, or at least 90 weight percent solids.

The non-BA byproduct rich stream in line 52 can have a relatively highercumulative concentration of non-BA byproducts on a weight basis comparedto the cumulative concentration of non-BA byproducts in the purge feedstream in line 42. In one embodiment of the present invention, thenon-BA byproduct rich stream in line 52 can have a cumulativeconcentration of non-BA byproducts that is at least about 1.5 times thecumulative concentration of non-BA byproducts in the purge feed streamon a weight basis, at least about 5 times the cumulative concentrationof non-BA byproducts in the purge feed stream on a weight basis, or atleast 10 times the cumulative concentration of non-BA byproducts in thepurge feed stream on a weight basis. In one embodiment, non-BAbyproducts can cumulatively be the primary oxidation byproducts in thenon-BA byproduct rich stream. The non-BA byproduct rich stream in line52 can be in the form of a wet cake, comprising in the range of fromabout 5 to about 30 weight percent liquid, in the range of from 10 toabout 25 weight percent liquid, or in the range of from 12 to 23 weightpercent liquid.

In one embodiment of the present invention, at least a portion of the BArich stream, the catalyst rich stream, and the non-BA byproduct richstream can be routed to different locations. Such locations include, butare not limited to, various points in a TPA production process, an IPAproduction process, a phthalic acid (PA) production process, a BAproduction process, a naphthalene-dicarboxylic acid (NDA) productionprocess, a dimethylterephthalate (DMT) production process, adimethylnaphthalate (DMN) production process, a cyclohexane dimethanol(CHDM) production process, a dimethyl-cyclohexanedicarboxylate (DMCD)production process, a cyclohexanedicarboxylic acid (CHDA) productionprocess, a polyethylene terephthalate (PET) production process, aproduction process for any isomers of NDA, DMT, DMN, CHDM, DMCD, CHDA, acopolyester production process, a polymer production process employingone or more of TPA, IPA, PA, BA, NDA, DMT, DMN, CHDM, DMCD, CHDA, or anyisomers thereof as one component and/or as a monomer, and/or outside theTPA, IPA, PA, BA, NDA, DMT, DMN, CHDM, DMCD, CHDA, PET, or polymerproduction processes.

In one embodiment, the amount of BA that exits the TPA productionprocess with the TPA product and/or is combined with the TPA productdownstream of the TPA production process can be sufficient to result ina TPA product comprising BA in an amount of less than about 1000 ppmw,less than about 500 ppmw, or less than 250 ppmw. In another embodiment,the rate at which BA exits the TPA production process with the TPAproduct and/or is combined with the TPA product downstream of the TPAproduction process can be less than about 50 percent, less than about 10percent, less than about 1 percent, or less than 0.1 percent of themake-rate of BA in the TPA production process. As used herein withreference to BA, when no purification step (e.g., purification zone 14)is employed in the TPA production process, the term “make-rate” isdefined as the difference between the mass per unit time of BA enteringthe oxidation step (e.g., oxidation zone 10) and the mass per unit timeof BA exiting the oxidation step. When a purification step is employedin the TPA production process, the term “make-rate” when referring to BAis defined as the difference between the mass per unit time of BAentering the oxidation step (e.g., oxidation zone 10) and the mass perunit time of BA exiting the purification step (e.g., purification zone14). By way of illustration, for a TPA production process that employs apurification step, if BA enters the oxidation step of the TPA productionprocess at a rate of 50 kilograms per hour (kg/hr), and BA exits thepurification step at a rate of 150 kg/hr, then the make-rate of BA inthe TPA production process is 100 kg/hr.

In another embodiment, at least a portion of the BA rich stream can exitthe process depicted in FIG. 1 and be routed to a purification andrecovery process, a subsequent chemical process, and/or a wastetreatment or disposal process. Such waste treatment or disposalprocesses include, but are not limited to, sale, burial, incineration,neutralization, anaerobic and/or aerobic digestion, treatment in a wasteoxidizer, and/or treatment in a waste reactor. In one embodiment of thepresent invention, at least a portion of the BA rich stream can berouted to a waste treatment process where at least about 50 weightpercent, at least about 60 weight percent, or at least 70 weight percentof the BA present in the BA rich stream is treated.

As mentioned above, the catalyst rich stream in line 50 can be routed tovarious points in a TPA production process. In one embodiment of thepresent invention, at least a portion of the catalyst rich stream inline 50 can be routed, either directly or indirectly, to oxidation zone10, where at least about 50 weight percent, at least about 60 weightpercent, or at least 70 weight percent of the catalyst components of thecatalyst rich stream are introduced into oxidization zone 10. In oneembodiment, prior to routing, a liquid can optionally be added to thecatalyst rich stream in line 50 to produce a reslurried catalyst richstream. The reslurried catalyst rich stream can comprise at least about35 weight percent liquid, at least about 50 weight percent liquid, or atleast 65 weight percent liquid. The liquid added to the catalyst richstream can be, for example, acetic acid and/or water.

Referring still to FIG. 1, as noted above, the non-BA byproduct richstream in line 52 can be routed to various points in the depicted TPAproduction process. Such routing includes, but is not limited to,returning at least a portion of the non-BA byproduct rich stream, eitherdirectly or indirectly, to oxidation zone 10 and/or purification zone14. In one embodiment, at least a portion of the non-BA byproduct richstream can be routed such that at least a portion of the non-BAbyproducts in said non-BA byproduct rich stream exit the TPA productionprocess with the dry TPA product discharged from line 24 and/or with thewet TPA product discharged from line 28. For example, at least a portionof the non-BA byproduct rich stream can be introduced into the purifiedslurry in line 16 and/or into the product slurry/cake in line 20 andallowed to exit the TPA production process with the TPA product. Inanother embodiment, at least a portion of the non-BA byproducts in thenon-BA byproduct rich stream can be combined with the TPA productdownstream of the TPA production process. In one embodiment, at leastabout 5 weight percent, at least about 25 weight percent, at least about50 weight percent, or at least 75 weight percent of the non-BAbyproducts in the non-BA byproduct rich stream can be allowed to exitthe TPA production process with the TPA product and/or can be combinedwith the TPA product downstream of the TPA production process.

In one embodiment, the cumulative rate at which the non-BA byproductsexit the TPA production process with the TPA product and/or are combinedwith the TPA product downstream of the TPA production process can be atleast about 5 percent, at least about 10 percent, at least about 20percent, or at least 50 percent of the make-rate of the non-BAbyproducts in the TPA production process. As used herein with referenceto non-BA byproducts, when no purification step (e.g., purification zone14) is employed in the TPA production process, the term “make-rate” isdefined as the difference between the mass per unit time of non-BAbyproducts entering the oxidation step (e.g., oxidation zone 10) and themass per unit time of non-BA byproducts exiting the oxidation step. Whena purification step is employed in the TPA production process, the term“make-rate” when referring to non-BA byproducts is defined as thedifference between the mass per unit time of non-BA byproducts enteringthe oxidation step (e.g., oxidation zone 10) and the mass per unit timeof non-BA byproducts exiting the purification step (e.g., purificationzone 14). By way of illustration, for a TPA production process thatemploys a purification step, if non-BA byproducts enter the oxidationstep of the TPA production process at a rate of 50 kg/hr, and non-BAbyproducts exit the purification step at a rate of 150 kg/hr, then themake-rate of non-BA byproducts in the TPA production process is 100kg/hr.

In another embodiment, the non-BA byproduct rich stream can exit theprocess depicted in FIG. 1 and can be routed to a purification andrecovery process, a process utilizing non-BA byproducts for makingnon-BA byproduct derivatives, and/or a waste treatment or disposalprocess. Such waste treatment or disposal processes include, but are notlimited to, sale, burial, incineration, neutralization, anaerobic and/oraerobic digestion, treatment in a waste oxidizer, and/or treatment in awaste reactor.

As mentioned above, the non-BA byproduct rich stream in line 52 can bein the form of a wet cake. In one embodiment of the present invention,prior to routing the non-BA byproduct rich stream, at least a portionthe non-BA byproduct rich stream may optionally be dried in drying zone54. Drying zone 54 can comprise any drying device known in the art thatcan produce a dried non-BA byproduct rich stream comprising less thanabout 5 weight percent liquid, less than about 3 weight percent liquid,or less than 1 weight percent liquid. The optionally dried non-BAbyproduct rich stream can be discharged from drying zone 54 via line 56.

In another embodiment, prior to routing the non-BA byproduct richstream, a liquid may be added to at least a portion of the non-BAbyproduct rich stream in reslurry zone 58 to produce a reslurried non-BAbyproduct rich stream. The reslurried non-BA byproduct rich stream canbe discharged from reslurry zone 58 via line 60. The reslurried non-BAbyproduct rich stream can comprise at least about 35 weight percentliquid, at least about 50 weight percent liquid, or at least 65 weightpercent liquid. The liquid added to the non-BA byproduct rich stream inreslurry zone 58 can comprise acetic acid and/or water.

FIG. 2 illustrates an overview of one embodiment of purge treatment zone100, briefly discussed above with reference to FIG. 1. In the embodimentof FIG. 2, purge treatment zone 100 comprises a non-BA byproduct removalzone 102 and a BA removal zone 104. The purge feed stream in line 42 caninitially be introduced into non-BA byproduct removal zone 102. As willbe discussed in greater detail below, non-BA byproduct removal zone 102can separate the purge feed stream into the above-mentioned non-BAbyproduct rich stream and a catalyst and BA rich mother liquor (i.e., acatalyst and mono-functional impurity rich mother liquor). The non-BAbyproduct rich stream can be discharged from non-BA byproduct removalzone 102 via line 52, and the catalyst and BA rich mother liquor can bedischarged via line 106.

In one embodiment of the present invention, the catalyst and BA richmother liquor in line 106 can comprise one or more catalyst components,BA, and solvent. The catalyst and BA rich mother liquor can comprisesolids in an amount of less than about 5 weight percent, less than about3 weight percent, or less than 1 weight percent. The solvent in thecatalyst and BA rich mother liquor can comprise acetic acid and/orwater. The catalyst components in the catalyst and BA rich mother liquorcan comprise cobalt, manganese, and/or bromine, as discussed above inrelation to the catalyst system introduced into oxidation zone 10 ofFIG. 1.

The catalyst and BA rich mother liquor in line 106 can have a relativelyhigher concentration of BA and catalyst components on a weight basiscompared to the concentration of BA and catalyst components in the purgefeed stream in line 42. In one embodiment, the catalyst and BA richmother liquor in line 106 can have a cumulative concentration of all ofthe catalyst components that is at least about 1.5 times the cumulativeconcentration of all of the catalyst components in the purge feed streamon a weight basis, at least about 5 times the cumulative concentrationof all of the catalyst components in the purge feed stream on a weightbasis, or at least 10 times the cumulative concentration of all of thecatalyst components in the purge feed stream on a weight basis.Furthermore, the catalyst and BA rich mother liquor in line 106 can havea concentration of BA that is at least about 1.5 times the concentrationof BA in the purge feed stream on a weight basis, at least about 5 timesthe concentration of BA in the purge feed stream on a weight basis, orat least 10 times the concentration of BA in the purge feed stream on aweight basis.

In the embodiment of FIG. 2, the catalyst and BA rich mother liquor canbe introduced into BA removal zone 104 via line 106. As will bediscussed in greater detail below, BA removal zone 104 can separate thecatalyst and BA rich mother liquor into the above-mentioned BA richstream and the above-mentioned catalyst rich stream. The BA rich streamcan be discharged from BA removal zone 104 via line 48 and the catalystrich stream can be discharged via line 50.

FIG. 3 illustrates in detail one configuration of non-BA byproductremoval zone 102 and BA removal zone 104. In the embodiment of FIG. 3,non-BA byproduct removal zone 102 comprises concentration section 202and solid/liquid separation section 208. In this embodiment, the purgefeed stream can initially be introduced into concentration section 202via line 42. Concentration section 202 can operate to remove at least aportion of the volatile compounds contained in the purge feed stream. Inone embodiment, the volatile compounds comprise at least a portion ofthe solvent in the purge feed stream. The solvent can comprise waterand/or acetic acid. Concentration section 202 can remove at least about30, at least about 45, or at least 60 weight percent of the volatilecompounds in the purge feed stream. Volatile compounds can be dischargedfrom concentration section 202 via line 204. In one embodiment of thepresent invention, at least a portion of the volatiles in line 204 canbe routed, either directly or indirectly, to oxidation zone 10 depictedin FIG. 1.

Any equipment known in the industry capable of removing at least aportion of the volatile compounds from the purge feed stream may beemployed in concentration section 202. Examples of suitable equipmentinclude, but are not limited to, one or more evaporators. In oneembodiment, concentration section 202 can comprise at least twoevaporators. When two evaporators are employed, each one individuallycan be operated under vacuum at reduced temperature, or can be operatedat elevated temperature and pressure. In one embodiment, each evaporatorcan be operated at a temperature in the range of from about 40 to about180° C. and a pressure in the range of from about 50 to about 4500 torrduring concentration. Suitable equipment for use in concentrationsection 202 includes, but is not limited to, a simple agitated tank, aflash evaporator, an advancing front crystallizer, a thin filmevaporator, a scraped thin film evaporator, and/or a falling filmevaporator.

In the embodiment of FIG. 3, a concentrated purge feed stream can bedischarged from concentration section 202 via line 206. The solidscontent of the concentrated purge feed stream in line 206 can be atleast about 1.5 times, at least about 5 times, or at least 10 times thesolids content of the unconcentrated purge feed stream in line 42, wheresolids content is measured on a weight basis. The concentrated purgefeed stream can comprise solids in an amount in the range of from about5 to about 70 weight percent, or in the range of from 10 to 40 weightpercent. Also, the concentrated purge feed stream can comprise one ormore catalyst components, BA and non-BA oxidation byproducts, TPAparticles, and solvent, each as discussed above.

The concentrated purge feed stream can be introduced into solid/liquidseparation section 208 via line 206. Solid/liquid separation section 208can separate the concentrated purge feed stream into a predominatelyfluid phase catalyst and BA rich mother liquor and a wet cake. In theembodiment of FIG. 3, solid/liquid separation section 208 comprisesmother liquor removal section 208 a and wash section 208 b. Motherliquor removal section 208 a can operate to separate the concentratedpurge feed stream into the above-mentioned catalyst and BA rich motherliquor and an initial wet cake. The catalyst and BA rich mother liquorcan be discharged from mother liquor removal section 208 a via line 106.The initial wet cake can be introduced into wash section 208 b. At leasta portion of the initial wet cake can then be washed with the wash feedintroduced into wash section 208 b via line 210 to produce a washed wetcake. The wash feed in line 210 can comprise water and/or acetic acid.Furthermore, the wash feed can have a temperature in the range of fromabout the freezing point of the wash feed to about the boiling point ofthe wash feed, in the range of from about 20 to about 110° C., or in therange of from 40 to 90° C. The wash feed can operate to remove at leasta portion of catalyst components from the wet cake. After washing thewet cake, the resulting wash liquor can be discharged from wash section208 b via line 212, and the washed wet cake can be discharged via line52. In one embodiment, the above-mentioned non-BA byproduct rich streamcomprises at least a portion of the washed wet cake.

Solid/liquid separation section 208 can comprise any solid/liquidseparation device known in the art. Suitable equipment for use insolid/liquid separation section 208 includes, but is not limited to, apressure drum filter, a vacuum drum filter, a vacuum belt filter,multiple solid bowl centrifuges with counter current wash, or aperforated centrifuge. In one embodiment, solid/liquid separationsection 208 can be operated at a temperature in the range of from about20 to about 170° C. and a pressure in the range of from about 375 toabout 4500 torr during separation.

As mentioned above, the wash liquor can be discharged from solid/liquidseparation section 208 via line 212. In one embodiment, at least aportion of the wash liquor in line 212 can be routed, either directly orindirectly, to oxidation zone 10 as depicted in FIG. 1. Optionally, atleast a portion of the wash liquor in line 212 can be concentrated priorto introduction in oxidation zone 10. The optional concentrator can beany device known in the art capable of concentrating the wash liquorstream, such as, for example, membrane separation or evaporation. Inanother embodiment, at least a portion of the wash liquor in line 212can be routed to a waste treatment facility.

Referring still to FIG. 3, BA removal zone 104 comprises concentrationsection 214 and BA/catalyst separation section 220. In one embodiment,the catalyst and BA rich mother liquor in line 106 can initially beintroduced into concentration section 214. Concentration section 214 canoperate to remove at least a portion of the volatile compounds containedin the catalyst and BA rich mother liquor. In one embodiment, thevolatile compounds comprise at least a portion of the solvent in thecatalyst and BA rich mother liquor. The solvent can comprise waterand/or acetic acid. Concentration section 214 can remove at least about50, at least about 70, or at least 90 weight percent of the solvent inthe catalyst and BA rich mother liquor. Evaporated compounds can bedischarged from concentration section 214 via line 216.

Any equipment known in the industry capable of removing at least aportion of the volatile compounds from the catalyst and BA rich motherliquor can be employed in concentration section 214. Examples ofsuitable equipment include, but are not limited to, a simple agitatedtank, a flash evaporator, an advancing front crystallizer, a thin filmevaporator, a scraped thin film evaporator, or a falling filmevaporator. In one embodiment, concentration section 214 can be operatedat a pressure in the range of from about 50 to about 800 torr duringconcentration. Additionally, concentration section 214 can be operatedat a temperature of at least about 120° C., or at least 130° C. duringconcentration.

In the embodiment of FIG. 3, a concentrated catalyst and BA rich motherliquor (i.e., a mono-functional impurity rich slurry) can be dischargedfrom concentration section 214 via line 218. The concentrated catalystand BA rich mother liquor can comprise one or more catalyst components,BA, and solvent. The concentration of all the catalyst components and BAof the concentrated catalyst and BA rich mother liquor can be at leastabout 1.5 times, at least about 5 times, or at least 10 times theconcentration of all the catalyst components and BA of theunconcentrated catalyst and BA rich mother liquor in line 106.

The concentrated catalyst and BA rich mother liquor can be introducedinto BA/catalyst separation section (i.e., mono-functional impurityremoval section) 220 via line 218. BA/catalyst separation section 220operates to separate the concentrated catalyst and BA rich mother liquorinto the above-mentioned catalyst rich stream and the above-mentioned BArich stream. In one embodiment, separation of the concentrated catalystand BA rich mother liquor can be accomplished by evaporating andremoving at least a portion of the BA in the concentrated catalyst andBA rich mother liquor. Any dryer known in the art that can evaporate andremove at least about 50 weight percent, at least about 70 weightpercent, or at least 90 weight percent of the BA in the concentratedcatalyst and BA rich mother liquor can be used. A suitable example of acommercially available dryer that can be employed in BA/catalystseparation section 220 includes, but is not limited to, a LIST dryer. Inone embodiment, BA/catalyst separation section 220 can be operated at atemperature in the range of from about 170 to about 250° C. and apressure in the range of from about 50 to about 760 torr duringseparation. The catalyst rich stream can be discharged from BA/catalystseparation section 220 via line 50, and the BA rich stream can bedischarged via line 48.

FIG. 4 illustrates in detail a second configuration of non-BA byproductremoval zone 102 and BA removal zone 104. Non-BA byproduct removal zone102 comprises concentration section 302 and solid/liquid separationsection 308. In the embodiment of FIG. 4, concentration section 302 andsolid/liquid separation section 308 are operated in substantially thesame manner as discussed above with reference to concentration section202 and solid/liquid separation section 208 of FIG. 3. Additionally, thecomposition and treatment of the volatiles in line 304, the concentratedpurge feed stream in line 306, the wash feed in line 310, and the washliquor in line 312 are substantially the same as discussed above withreference to the volatiles in line 204, the concentrated purge feedstream in line 206, the wash feed in line 210, and the wash liquor inline 212 of FIG. 3. The above-mentioned non-BA byproduct rich stream canbe discharged from solid/liquid separation section 308 via line 52, andthe above-mentioned catalyst and BA rich mother liquor can be dischargedvia line 106.

In the embodiment of FIG. 4, BA removal zone 104 comprises catalystremoval section 314 and BA/solvent separation section 318. In oneembodiment, the catalyst and BA rich mother liquor in line 106 caninitially be introduced into catalyst removal section 314. Catalystremoval section 314 can operate to remove at least a portion of the BAand solvent in the catalyst and BA rich mother liquor, generating theabove-mentioned catalyst rich stream and a BA and solvent rich stream(i.e., a mono-functional impurity and solvent rich stream). Removal ofBA and solvent in catalyst removal section 314 can be accomplished byevaporating and removing at least a portion of the BA and solvent fromthe catalyst and BA rich mother liquor. In one embodiment, at leastabout 50 weight percent, at least about 70 weight percent, or at least90 weight percent of the BA and solvent in the catalyst and BA richmother liquor can be removed in catalyst removal section 314. Any dryerknown in the art that can evaporate and remove at least a portion of theBA and solvent in the catalyst and BA rich mother liquor can be used. Asuitable example of a commercially available dryer that can be employedin catalyst removal section 314 includes, but is not limited to, a LISTdryer. In one embodiment, catalyst removal 314 can be operated at atemperature in the range of from about 170 to about 250° C. and apressure in the range of from about 50 to about 760 torr during catalystremoval.

As mentioned above, catalyst removal zone 314 generates the catalystrich stream and a BA and solvent rich stream. The catalyst rich streamcan be discharged from catalyst removal zone 314 via line 50. The BA andsolvent rich stream can be discharged from catalyst removal section 314via line 316. In one embodiment, the BA and solvent rich stream can be apredominately fluid phase stream and can comprise at least two portionshaving different volatilities (i.e., a lower volatility portion and ahigher volatility portion). The lower volatility portion can comprise BAand the higher volatility portion can comprise solvent. The solvent cancomprise acetic acid and/or water.

In the embodiment of FIG. 4, the BA and solvent rich stream can beintroduced into BA/solvent separation section (i.e., mono-functionalimpurity/solvent separation section) 318 via line 316. BA/solventseparation section 318 can separate the BA and solvent rich stream intothe above-mentioned BA rich stream and a solvent rich stream. Theseparation of the BA and solvent rich stream can be accomplished byfluid/fluid separation. Any fluid/fluid separation device known in theart capable of separating two fluid phases may be used in BA/solventseparation section 318. Such devices include, but are not limited to, adryer, an evaporator, a partial condenser, and/or distillation devices.In one embodiment, BA/solvent separation section 318 can be operated ata temperature in the range of from about 170 to about 250° C. and apressure in the range of from about 50 to about 760 torr duringseparation.

The BA rich stream can be discharged from BA/solvent separation section318 via line 48. The solvent rich stream can be discharged fromBA/solvent separation section 314 via line 320. In one embodiment, thesolvent rich stream can comprise a higher concentration of solvent thanthe BA and solvent rich stream in line 316. The solvent rich stream canhave a concentration of solvent that is at least about 1.5 times theconcentration of solvent in the BA and solvent rich stream on a weightbasis, at least about 5 times the concentration of solvent in thesolvent and BA rich stream on a weight basis, or at least 10 times theconcentration of solvent in the solvent and BA rich stream on a weightbasis. In one embodiment, at least a portion of the solvent rich streamin line 320 can be routed, either directly or indirectly, to oxidationzone 10 depicted in FIG. 1.

FIG. 5 illustrates an overview of another embodiment of purge treatmentzone 100, briefly discussed above with reference to FIG. 1. In theembodiment of FIG. 5, purge treatment zone 100 comprises BA removal zone400 and non-BA byproduct removal zone 402. The purge feed stream in line42 can initially be introduced into BA removal zone 400. As will bediscussed in greater detail below, BA removal zone 400 can separate thepurge feed stream into the above-mentioned BA rich stream and a catalystand non-BA byproduct rich stream (i.e., a catalyst andnon-mono-functional impurity rich stream). The BA rich stream can bedischarged from BA removal zone 400 via line 48, and the catalyst andnon-BA byproduct rich stream can be discharged via line 404.

In one embodiment of the present invention, the catalyst and non-BAbyproduct rich stream can comprise one or more catalyst components,non-BA byproducts, and solvent. Depending of the temperature andpressure of the catalyst and non-BA byproduct rich stream upon exitingBA removal zone 400, the catalyst and non-BA byproduct rich stream inline 404 can predominately comprise solids or fluid. Thus, in oneembodiment, the catalyst and non-BA byproduct rich stream in line 404can comprise at least about 50 weight percent fluid, at least about 70weight percent fluid, or at least 90 weight percent fluid. In analternate embodiment, the catalyst and non-BA byproduct rich stream inline 404 can comprise at least about 50 weight percent solids, at leastabout 70 weight percent solids, or at least 90 weight percent solids.The solvent in the catalyst and non-BA byproduct rich stream cancomprise acetic acid and/or water. The catalyst components in thecatalyst and non-BA byproduct rich stream can comprise cobalt,manganese, and/or bromine, as discussed above in relation to thecatalyst system introduced into oxidation zone 10 of FIG. 1.

The catalyst and non-BA byproduct rich stream in line 404 can have arelatively higher concentration of catalyst components and non-BAbyproducts on a weight basis compared to the concentration of catalystcomponents and non-BA byproducts in the purge feed stream in line 42. Inone embodiment, the catalyst and non-BA byproduct rich stream in line404 can have a cumulative concentration of all of the catalystcomponents that is at least about 1.5 times the cumulative concentrationof all of the catalyst components in the purge feed stream on a weightbasis, at least about 5 times the cumulative concentration of all of thecatalyst components in the purge feed stream on a weight basis, or atleast 10 times the cumulative concentration of all of the catalystcomponents in the purge feed stream on a weight basis. Furthermore, thecatalyst and non-BA byproduct rich stream in line 404 can have acumulative concentration of non-BA byproducts that is at least about 1.5times the cumulative concentration of non-BA byproducts in the purgefeed stream on a weight basis, at least about 5 times the cumulativeconcentration of non-BA byproducts in the purge feed stream on a weightbasis, or at least 10 times the cumulative concentration of non-BAbyproducts in the purge feed stream on a weight basis.

In the embodiment of FIG. 5, the catalyst and non-BA byproduct richstream can be introduced into non-BA byproduct removal zone 402 via line404. As will be discussed in greater detail below, non-BA byproductremoval zone 402 can separate the catalyst and non-BA byproduct richstream into the above-mentioned non-BA byproduct rich stream and theabove-mentioned catalyst rich stream. The non-BA byproduct rich streamcan be discharged from non-BA byproduct removal zone 402 via line 52 andthe catalyst rich stream can be discharged via line 50.

FIG. 6 illustrates in detail one configuration of BA removal zone 400and non-BA byproduct removal zone 402. In the embodiment of FIG. 6, BAremoval zone 400 comprises concentration section 502 and BA separationsection 508. In this embodiment, the purge feed stream in line 42 caninitially be introduced into concentration section 502. Concentrationsection 502 can operate to remove at least a portion of the volatilecompounds contained in the purge feed stream. Concentration section 502is operated in substantially the same manner as discussed above withreference to concentration section 202 of FIG. 3. Volatiles can bedischarged from concentration section 502 via line 504. The compositionand treatment of the volatiles in line 504 is substantially the same asdiscussed above with reference to the volatiles in line 204 of FIG. 3. Aconcentrated purge feed stream can be discharged from concentrationsection 502 via line 506. The composition of the concentrated purge feedstream in line 506 is substantially the same as discussed above withreference to the concentrated purge feed stream in line 206 of FIG. 3.

Referring still to FIG. 6, the concentrated purge feed stream in line506 can be introduced into BA separation section (i.e., mono-functionalimpurity removal section) 508. BA separation section 508 can operate toseparate the concentrated purge feed stream into the above-mentioned BArich stream and the above-mentioned catalyst and non-BA byproduct richstream. In one embodiment, BA separation can be achieved by evaporatingand removing at least a portion of the BA from the concentrated purgefeed stream. The evaporation can be achieved by heating the concentratedpurge feed stream in BA separation section 508 to at least about 123° C.at atmospheric pressure. In another embodiment, BA separation section508 can be operated at a pressure in the range of from about 50 to about760 torr during evaporation. Additionally, BA separation section 508 canbe operated at a temperature in the range of from about 123 to about250° C. during evaporation. At least about 40 weight percent, at leastabout 70 weight percent, or at least 90 weight percent of the BAcontained in the concentrated purge feed stream can be removed in BAseparation section 508. Equipment suitable for use in BA separationsection 508 includes, but is not limited to, a LIST dryer, a potdistillation device, a partial condenser, or a thin film evaporator. TheBA rich stream can be discharged from BA separation section 508 via line48, and the catalyst and non-BA byproduct rich stream can be dischargedvia line 404.

In the embodiment of FIG. 6, non-BA byproduct removal zone 402 comprisesreslurry section 510 and solid/liquid separation section 516. In oneembodiment, the catalyst and non-BA byproduct rich stream in line 404can initially be introduced into reslurry section 510. Reslurry section510 can be operated to add a liquid to the catalyst and non-BA byproductrich stream, thereby generating a reslurried catalyst and non-BAbyproduct rich stream. The liquid added to the catalyst and non-BAbyproduct rich stream in reslurry section 510 can be introduced intoreslurry section 510 via line 512. In one embodiment, the liquid in line512 can be a solvent, which can comprise acetic acid and/or water.Equipment suitable for use in reslurry section 510 can include anyequipment known in the art that can accomplish mixing a liquid streamand a solid stream to generate a slurry. Optionally, reslurry section510 can comprise a step of crystallization in order to increase particlesize distribution.

The reslurried catalyst and non-BA byproduct rich stream can bedischarged from reslurry section 510 via line 514. In one embodiment,the reslurried catalyst and non-BA byproduct rich stream can compriseone or more catalyst components, non-BA byproducts, and/or solvent. Thesolvent can comprise acetic acid and/or water. The catalyst componentscan comprise cobalt, manganese, and/or bromine, as discussed above inrelation to the catalyst system introduced into oxidation zone 10 ofFIG. 1. The reslurried catalyst and non-BA byproduct rich stream cancomprise solids in an amount in the range of from about 0 to about 65weight percent, or in the range of from 10 to 40 weight percent.

The reslurried catalyst and non-BA byproduct rich stream can beintroduced into solid/liquid separation section 516 via line 514.Solid/liquid separation section 514 can separate the reslurried catalystand non-BA byproduct rich stream into a predominately fluid phase motherliquor (e.g., the above-mentioned catalyst rich stream) and a wet cake.In the embodiment of FIG. 6, solid/liquid separation section 516comprises mother liquor removal section 516 a and wash section 516 b.Mother liquor removal section 516 a can operate to separate thereslurried catalyst and non-BA byproduct rich stream into theabove-mentioned catalyst rich stream and an initial wet cake. Thecatalyst rich stream can be discharged from mother liquor removalsection 516 a via line 50. The initial wet cake can be introduced intowash section 516 b. At least a portion of the initial wet cake can thenbe washed with the wash feed introduced into wash section 516 b via line518 to produce a washed wet cake. The wash feed in line 518 can comprisewater and/or acetic acid. The wash feed can operate to remove at least aportion of catalyst components from the wet cake. After washing the wetcake, the resulting wash liquor can be discharged from wash section 516b via line 520, and the washed wet cake can be discharged via line 52.In one embodiment, the above-mentioned non-BA byproduct rich stream cancomprise at least a portion of the washed wet cake.

Solid/liquid separation section 516 can comprise any solid/liquidseparation device known in the art. Suitable equipment that can be usedin solid/liquid separation section 516 includes, but is not limited to,a pressure drum filter, a vacuum drum filter, a vacuum belt filter,multiple solid bowl centrifuges with counter current wash, or aperforated centrifuge. In one embodiment, solid/liquid separationsection 516 can be operated at a temperature in the range of from about20 to about 170° C. and a pressure in the range of from about 375 toabout 4500 torr during separation.

As mentioned above, the wash liquor can be discharged from solid/liquidseparation section 516 via line 520. In one embodiment, at least aportion of the wash liquor in line 520 can be routed, either directly orindirectly, to oxidation zone 10, as depicted in FIG. 1. Optionally, thewash liquor in line 520 can be concentrated prior to introduction inoxidation zone 10. The optional concentrator can be any device known inthe art capable of concentrating the wash liquor stream, such as, forexample, membrane separation or evaporation. In another embodiment, atleast a portion of the wash liquor in line 520 can be routed to a wastetreatment facility.

It will be understood by one skilled in the art that each of theabove-described embodiments, as well as any sub-parts of thoseembodiments, may be operated in a continuous or a non-continuous manner.Non-continuous operations include, but are not limited to, batch-wiseoperations, cyclical operations, and/or intermittent operations.

In some of the embodiments above, temperature ranges are provided for aspecified operation. For each of the above embodiments where atemperature range is provided, the temperature is defined as the averagetemperature of the substance in the given zone or section. By way ofillustration, as discussed above with reference to FIG. 1, a portion ofthe mother liquor in line 30 can optionally be treated in solids removalzone 32, where solids removal zone 32 can be operated at a temperaturein the range of from about 20 to about 195° C. This means that theaverage temperature of the mother liquor while in solids removal zone 32can be in the range of from about 20 to about 195° C.

Numerical Ranges

The present description uses numerical ranges to quantify certainparameters relating to the invention. It should be understood that whennumerical ranges are provided, such ranges are to be construed asproviding literal support for claim limitations that only recite thelower value of the range as well as claims limitation that only recitethe upper value of the range. For example, a disclosed numerical rangeof 10 to 100 provides literal support for a claim reciting “greater than10” (with no upper bounds) and a claim reciting “less than 100” (with nolower bounds).

Definitions

As used herein, the terms “comprising,” “comprises,” and “comprise” areopen-ended transition terms used to transition from a subject recitedbefore the term to one or more elements recited after the term, wherethe element or elements listed after the transition term are notnecessarily the only elements that make up the subject.

As used herein, the terms “including,” “includes,” and “include” havethe same open-ended meaning as “comprising,” “comprises,” and“comprise.”

As used herein, the terms “having,” “has,” and “have” have the sameopen-ended meaning as “comprising,” “comprises,” and “comprise.”

As used herein, the terms “containing,” “contains,” and “contain” havethe same open-ended meaning as “comprising,” “comprises,” and“comprise.”

As used herein, the terms “a,” “an,” “the,” and “said” mean one or more.

As used herein, the term “and/or,” when used in a list of two or moreitems, means that any one of the listed items can be employed by itselfor any combination of two or more of the listed items can be employed.For example, if a composition is described as containing components A,B, and/or C, the composition can contain A alone; B alone; C alone; Aand B in combination; A and C in combination; B and C in combination; orA, B, and C in combination.

CLAIMS NOT LIMITED TO DISCLOSED EMBODIMENTS

The forms of the invention described above are to be used asillustration only, and should not be used in a limiting sense tointerpret the scope of the present invention. Obvious modifications tothe exemplary embodiments, set forth above, could be readily made bythose skilled in the art without departing from the spirit of thepresent invention.

The inventors hereby state their intent to rely on the Doctrine ofEquivalents to determine and assess the reasonably fair scope of thepresent invention as pertains to any apparatus not materially departingfrom but outside the literal scope of the invention as set forth in thefollowing claims.

1. A process for treating a purge feed stream comprising oxidationbyproducts, wherein said oxidation byproducts include benzoic acid (BA)and non-BA byproducts, said process comprising: separating at least aportion of said purge feed stream into a BA rich stream and a non-BAbyproduct rich stream.
 2. The process of claim 1, further comprisingrouting at least a portion of said BA rich stream and at least a portionof said non-BA byproduct rich stream to different locations.
 3. Theprocess of claim 2, wherein said oxidation byproducts are produced in aterephthalic acid (TPA) production process.
 4. The process of claim 3,wherein said routing includes directing at least a portion of saidnon-BA byproduct rich stream to one or more locations that cause atleast about 5 weight percent of said non-BA byproducts present in saidnon-BA byproduct rich stream to exit said TPA production process with aTPA product produced therein and/or to be combined with said TPA productdownstream of said TPA production process.
 5. The process of claim 3,wherein said routing includes introducing at least a portion of saidnon-BA byproduct rich stream into said TPA production process at one ormore locations that cause at least a portion of said non-BA byproductspresent in said non-BA byproduct rich stream to exit said TPA productionprocess with a TPA product produced therein.
 6. The process of claim 5,wherein at least about 10 weight percent of said non-BA byproductspresent in said non-BA byproduct rich stream exits said TPA productionprocess with said TPA product.
 7. The process of claim 3, wherein saidrouting includes directing at least a portion of said BA rich streamoutside said TPA production process for sale, waste treatment, disposal,purification, recovery, destruction, and/or use in a subsequent chemicalprocess.
 8. The process of claim 7, wherein at least about 50 weightpercent of said BA present in said BA rich stream is treated in a wastetreatment process.
 9. The process of claim 2, wherein said differentlocations include various points in a TPA production process, anisophthalic acid (IPA) production process, a phthalic acid (PA)production process, a BA production process, a naphthalene-dicarboxylicacid (NDA) production process, a dimethylterephthalate (DMT) productionprocess, a dimethylnaphthalate (DMN) production process, a cyclohexanedimethanol (CHDM) production process, adimethyl-cyclohexanedicarboxylate (DMCD) production process, acyclohexanedicarboxylic acid (CHDA) production process, a polyethyleneterephthalate (PET) production process, a copolyester productionprocess, a polymer production process employing one or more of TPA, IPA,PA, BA, NDA, DMT, DMN, CHDM, DMCD, or CHDA as one component and/or as amonomer, and/or outside said TPA, IPA, PA, BA, NDA, DMT, DMN, CHDM,DMCD, CHDA, or polymer production processes.
 10. The process of claim 1,wherein said purge feed stream comprises less than about 5 weightpercent solids.
 11. The process of claim 1, wherein said non-BAbyproduct rich stream comprises at least about 70 weight percent solids.12. The process of claim 1, wherein said BA rich stream comprises atleast about 70 weight percent fluid.
 13. The process of claim 1, whereinsaid non-BA byproduct rich stream comprises in the range of from about 5to about 40 weight percent liquid.
 14. The process of claim 13, furthercomprising drying said non-BA byproduct rich stream to thereby produce adried non-BA byproduct stream comprising less than about 5 weightpercent liquid.
 15. The process of claim 13, further comprising adding aliquid to said non-BA byproduct rich stream to thereby produce areslurried non-BA byproduct stream comprising at least about 35 weightpercent liquid.
 16. The process of claim 1, wherein at least a portionof said oxidation byproducts are byproducts from the partial oxidationof an aromatic compound.
 17. The process of claim 16, wherein saidaromatic compound is para-xylene.
 18. The process of claim 1, whereinsaid non-BA byproducts comprise IPA, PA, trimellitic acid,2,5,4′-tricarboxybiphenyl, 2,5,4′-tricarboxybenzophenone, para-toluicacid (p-TAc), 4-carboxybenzaldehyde (4-CBA), naphthalene dicarboxylicacid, monocarboxyfluorenones, monocarboxyfluorenes, and/ordicarboxyfluorenones.
 19. The process of claim 1, wherein theconcentration of said BA in said BA rich stream is at least about 1.5times the concentration of said BA in said purge feed stream on a weightbasis.
 20. The process of claim 19, wherein the concentration of said BAin said purge feed stream is in the range of from about 500 to about150,000 ppmw.
 21. The process of claim 1, wherein the concentration ofsaid non-BA byproducts in said non-BA byproduct rich stream is at leastabout 1.5 times of the concentration of said non-BA byproducts in saidpurge feed stream on a weight basis.
 22. The process of claim 21,wherein the cumulative concentration of said non-BA byproducts in saidpurge feed stream is in the range of from about 500 to about 50,000ppmw.
 23. The process of claim 1, wherein the concentration of said BAin said BA rich stream is at least about 5 times the concentration ofsaid BA in said purge feed stream on a weight basis, wherein theconcentration of said non-BA byproducts in said non-BA byproduct richstream is at least about 5 times the concentration of said non-BAbyproducts in said purge feed stream on a weight basis.
 24. The processof claim 1, wherein said purge feed stream further comprises at leastabout 75 weight percent of a solvent.
 25. The process of claim 24,wherein said solvent comprises a monocarboxylic acid.
 26. The process ofclaim 24, wherein said solvent comprises acetic acid and/or water. 27.The process of claim 24, further comprising directly or indirectlyrouting at least a portion of said solvent back to an oxidizer withinwhich at least a portion of said oxidation byproducts are formed. 28.The process of claim 27, wherein at least about 50 weight percent ofsaid solvent contained in said purge feed stream is routed back to saidoxidizer.
 29. The process of claim 1, wherein said purge feed streamfurther comprises one or more catalyst components.
 30. The process ofclaim 29, wherein said catalyst components comprise cobalt, manganese,and/or bromine.
 31. The process of claim 29, further comprisingseparating said purge feed stream into said BA rich stream, said non-BAbyproduct rich stream, and a catalyst rich stream.
 32. The process ofclaim 31, further comprising routing at least a portion of said BA richstream, at least a portion of said non-BA byproduct rich stream, and atleast a portion of said catalyst rich stream to at least two differentlocations.
 33. The process of claim 32, wherein said oxidationbyproducts are produced in a TPA production process.
 34. The process ofclaim 33, wherein said routing includes introducing at least a portionof said catalyst rich stream into an oxidizer of said TPA process withinwhich at least a portion of said oxidation byproducts were formed. 35.The process of claim 34, wherein at least about 50 weight percent ofsaid catalyst components in said catalyst rich stream are introducedinto said oxidizer.
 36. The process of claim 31, wherein the cumulativeconcentration of all of said catalyst components in said catalyst richstream is at least about 1.5 times the concentration of said catalystcomponents in said purge feed stream on a weight basis.
 37. The processof claim 36, wherein the cumulative concentration of said catalystcomponents in said purge feed stream is in the range of from about 500to about 20,000 ppmw.
 38. The process of claim 31, wherein thecumulative concentration of all of said catalyst components in saidcatalyst rich stream is at least about 5 times the concentration of saidcatalyst components in said purge feed stream on a weight basis, whereinthe concentration of said BA in said BA rich stream is at least about 5times the concentration of said BA in said purge feed stream on a weightbasis, wherein the concentration of said non-BA byproducts in saidnon-BA byproduct rich stream is at least about 5 times the concentrationof non-BA byproducts in said purge feed stream on a weight basis. 39.The process of claim 31, wherein said separating includes separatingsaid purge feed stream into said non-BA byproduct rich stream and acatalyst and BA rich stream followed by separating said catalyst and BArich stream into said BA rich stream and a catalyst rich stream.
 40. Theprocess of claim 31, wherein said separating includes separating saidpurge feed stream into said BA rich stream and a catalyst and non-BAbyproduct rich stream followed by separating said catalyst and non-BAbyproduct rich stream into said non-BA byproduct rich stream and acatalyst rich stream.
 41. A terephthalic acid (TPA) production processcomprising: (a) oxidizing an aromatic compound to thereby produce aslurry comprising TPA and oxidation byproducts, wherein said oxidationbyproducts include benzoic acid (BA) and non-BA byproducts; and (b)substantially isolating said TPA from said slurry to thereby produce aTPA product, wherein the cumulative rate at which said non-BA byproductsexit said TPA production process with said TPA product and/or arecombined with said TPA product downstream of said TPA production processis at least about 5 percent of the make-rate of said non-BA byproductsin said TPA production process.
 42. The process of claim 41, wherein therate at which said BA exits said TPA production process with said TPAproduct and/or is combined with said TPA product downstream of said TPAproduction process is less than about 50 percent of the make-rate ofsaid BA in said TPA production process.
 43. The process of claim 41,wherein the cumulative rate at which said non-BA byproducts exit saidTPA production process with said TPA product and/or are combined withsaid TPA product downstream of said TPA production process is at leastabout 10 percent the make-rate of said non-BA byproducts in said TPAproduction process.
 44. The process of claim 41, wherein said isolatingof step (b) comprises subjecting said purified slurry to solid/liquidseparation to thereby produce a predominately solid phase streamcomprising at least a portion of said TPA product and a mother liquor,wherein said mother liquor comprises at least a portion of saidoxidation byproducts and one or more catalyst components.
 45. Theprocess of claim 44, said process further comprising directly orindirectly routing a first portion of said mother liquor to an oxidizerwhere said oxidizing of step (a) is carried out.
 46. The process ofclaim 44, said process further comprising diverting a second portion ofsaid mother liquor so as to form a purge feed stream and separating saidpurge feed stream into a BA rich stream, a non-BA byproduct rich stream,and a catalyst rich stream.
 47. The process of claim 46, furthercomprising routing at least a portion of said BA rich stream, at least aportion of said non-BA byproduct rich stream, and at least a portion ofsaid catalyst rich stream to at least two different locations.
 48. Theprocess of claim 47, wherein said routing includes introducing at leasta portion of said catalyst rich stream into an oxidizer where saidoxidizing of step (a) is carried out.
 49. The process of claim 47,wherein said routing includes introducing at least a portion of saidnon-BA byproduct rich stream into said TPA production process at one ormore locations that cause at least a portion of said non-BA byproductspresent in said non-BA byproduct rich stream to exit said TPA productionprocess with said TPA product.
 50. The process of claim 47, wherein saidrouting includes introducing at least a portion of said non-BA byproductrich stream into said slurry and/or said TPA product.
 51. The process ofclaim 47, wherein said routing includes directing at least a portion ofsaid BA rich stream outside said TPA production process for sale, wastetreatment, disposal, purification, recovery, destruction, and/or use ina subsequent chemical process.
 52. The process of claim 46, wherein saidpurge feed stream comprises less than about 5 weight percent solids,wherein said catalyst rich stream comprises at least about 70 weightpercent solids, wherein said BA rich stream comprises at least about 70weight percent liquid, wherein said non-BA byproduct rich streamcomprises in the range of from about 5 to about 30 weight percentliquid.
 53. The process of claim 46, wherein the concentration of saidBA in said BA rich stream is at least about 1.5 times the concentrationof said BA in said purge feed stream on a weight basis, wherein theconcentration of said non-BA byproducts in said non-BA byproduct richstream is at least about 1.5 times of the concentration of said non-BAbyproducts in said purge feed stream on a weight basis, wherein theconcentration of said catalyst components in said catalyst rich streamis at least about 1.5 times the concentration of said catalystcomponents in said purge feed stream on a weight basis.
 54. The processof claim 41, step (a) further comprising subjecting at least a portionof said slurry to purification to thereby produce a purified slurrycomprising at least a portion of said TPA and at least a portion of saidoxidation byproducts.
 55. The process of claim 54, wherein saidpurification comprises hydrogenation and/or oxidation.
 56. The processof claim 41, wherein said non-BA byproducts comprise IPA, PA,trimellitic acid, 2,5,4′-tricarboxybiphenyl,2,5,4′-tricarboxybenzophenone, p-TAc, 4-CBA, naphthalene dicarboxylicacid, monocarboxyfluorenones, monocarboxyfluorenes, and/ordicarboxyfluorenones.
 57. The process of claim 41, wherein said TPAproduct comprises a cumulative concentration of mono-functionaloxidation byproducts of less than about 1,000 ppmw.
 58. The process ofclaim 57, wherein said mono-functional oxidation byproducts comprise BA,4-CBA, p-TAc, monocarboxyfluorenones, monocarboxyfluorenes,bromo-benzoic acid, and/or bromo-acetic acid.
 59. A process for treatinga purge feed stream comprising impurities and one or more catalystcomponents, said process comprising: separating said purge feed streaminto a mono-functional impurity rich stream, a mono-functional impuritydepleted stream, and a catalyst rich stream.
 60. The process of claim59, wherein said impurities include oxidation byproducts.
 61. Theprocess of claim 60, wherein said oxidation byproducts include benzoicacid, isophthalic acid, p-toluic acid (p-TAc), and/or4-carboxybenzaldehyde.
 62. The process of claim 59, wherein said purgefeed stream further comprises solvent, water, and/or terephthalic acid.63. The process of claim 59, wherein said purge feed stream comprisesless than about 5 weight percent solids.
 64. The process of claim 59,wherein said impurities comprise mono-functional impurities andnon-mono-functional impurities, wherein said mono-functional impuritiescomprise at least one monocarboxylic species.
 65. The process of claim64, wherein said mono-functional impurities comprise benzoic acid,p-TAc, monocarboxyfluorenones, monocarboxyfluorenes, bromo-benzoic acid,and/or bromo-acetic acid.
 66. The process of claim 60, wherein benzoicacid (BA) is the primary oxidation byproduct present in saidmono-functional impurity rich stream.
 67. The process of claim 60,wherein non-BA oxidation byproducts are the primary oxidation byproductspresent in said mono-functional impurity depleted stream.
 68. Theprocess of claim 67, wherein said non-BA oxidation byproducts includeisophthalic acid and/or trimellitic acid.
 69. The process of claim 59,wherein said catalyst components comprise cobalt, manganese, and/orbromine.
 70. The process of claim 59, further comprising routing atleast a portion of said mono-functional impurity rich stream, at least aportion of said mono-functional impurity depleted stream, and at least aportion of said catalyst rich stream to at least two differentlocations.
 71. The process of claim 70, wherein said impurities areproduced in a terephthalic acid (TPA) production process.
 72. Theprocess of claim 71, wherein said routing includes directing at least aportion of said mono-functional impurity rich stream outside said TPAproduction process for sale, waste treatment, disposal, and/ordestruction.
 73. The process of claim 71, wherein non-mono-functionaloxidation byproducts are the primary oxidation byproducts present insaid mono-functional impurity depleted stream, wherein said routingincludes directing at least a portion of said mono-functional impuritydepleted stream to one or more locations that cause a substantialportion of said non-mono-functional oxidation byproducts present in saidmono-functional impurity depleted stream to exit said TPA productionprocess with a TPA product produced therein and/or to be combined withsaid TPA product downstream of said TPA production process.
 74. Theprocess of claim 73, wherein said TPA product comprises a cumulativeconcentration of mono-functional oxidation byproducts of less than about1,000 ppmw.
 75. The process of claim 70, wherein said routing includesintroducing at least a portion of said catalyst rich stream into anoxidizer within which said impurities are formed.
 76. The process ofclaim 70, wherein said different locations include various points in apolymer production process employing terephthalic acid as one componentand/or as a monomer, said TPA production process, a polyethyleneterephthalate (PET) production process, and/or outside said polymer,TPA, or PET production processes.